Download iron in microbial metabolisms

IRON IN MICROBIAL
METABOLISMS
Kurt O. Konhauser1, Andreas Kappler2, and Eric E. Roden3
1811-5209/11/0007-0089$2.50 DOI: 10.2113/gselements.7.2.89
M
icrobes are intimately involved in the iron cycle. First, acquisition
of iron by microorganisms for biochemical requirements is a key
process in the iron cycle in oxygenated, circumneutral pH environments, where the solubility of Fe(III) (oxyhydr)oxides is extremely low.
Second, a number of aerobic (using O2 ) and anaerobic (living in the absence
of O2 ) autotrophic bacteria gain energy for growth from the oxidation of
dissolved and solid-phase Fe(II) compounds to Fe(III) (oxyhydr)oxides. Third,
heterotrophic Fe(III)-reducing bacteria close the chemical loop by reducing
solid-phase Fe(III) minerals back to dissolved and solid-phase Fe(II). Together
these metabolic processes control the partitioning of the Earth’s fourth most
abundant crustal element, and they are additionally tied to the cycling of
several major nutrients (e.g. carbon, oxygen, nitrogen, sulfur) and trace
elements (e.g. phosphorus, nickel) in modern and ancient environments.
Keywords : iron, bacteria, metabolism, oxidation, reduction, autotrophic
bacteria, heterotrophic bacteria
INTRODUCTION
Iron is essential to nearly all known organisms. In animals,
iron forms an organic complex known as heme that serves
as the structural backbone to proteins such as hemoglobin.
These proteins are found in red blood cells and are responsible for carrying oxygen from the lungs to the rest of the
body. Heme is also found in the center of a number of
metalloenzymes (proteins that contain a metal ion) that
play a role in cellular metabolism. One of the most important metalloenzymes is cytochrome. It facilitates the
transfer of electrons sourced from reduced molecules, such
as organic carbon, to oxygen, and in the process the animal
harnesses energy for cellular functions and growth. Ferritin
is a protein used by almost all livings organisms to store
and release iron, and in humans, it acts as a buffer against
iron deficiency or iron toxicity.
The poor solubility of ferric iron minerals at circumneutral
pH values and their correspondingly low dissolved Fe(III)
concentrations (~10 –10 mol per liter) mean that iron is often
a limiting nutrient for growth under oxygenated conditions. Many bacteria and fungi get around this impasse by
excreting low molecular weight organic compounds known
as siderophores that specifically complex dissolved Fe(III).
Indeed, siderophores or their breakdown products can be
so abundant that they dominate ferric iron speciation in
surface ocean water and soils (e.g. Wilhelm and Trick 1994).
Siderophores have two properties that make them ideal
Fe(III) scavengers: they are soluble, and they provide reactive sites (known as ligands) that can bind to the central
Fe(III) cation. Significantly, they form especially strong
surface complexes, and their binding capacity for Fe(III)
can be several times higher than that of common soil
organic acids (e.g. oxalic acid). This is an important property because it maintains ferric iron in a dissolved form,
which minimizes its loss from the aqueous environment
by the precipitation of solid-phase ferric (oxyhydr)oxides
(Hider 1984).
The biosynthesis of siderophores is tightly controlled by
iron levels. When dissolved Fe(III) concentrations are low,
siderophore production becomes activated by the presence
of minerals containing ferric iron: the more insoluble the
iron source the more siderophores are produced (e.g.
Hersman et al. 2000). In fact, many microorganisms
produce siderophores in great excess of their requirements
because a large proportion of the siderophores are lost via
diffusion and advection. Other studies have documented
1 Department of Earth and Atmospheric Sciences University of Alberta
Edmonton, Alberta T6G 2E3, Canada
E-mail: [email protected]
2 Geomicrobiology, Center for Applied Geosciences University of Tübingen
Sigwartstrasse 10, 72076 Tübingen, Germany
3 Department of Geosciences, University of Wisconsin–Madison
Madison, WI 53706, USA
pp.
89–93
Why Fe became important for so
many enzymes is almost certainly
related to the origin and early
evolution of life. According to the
“Wächtershäuser theory,” primitive forms of metalloenzymes may
have played a key role in catalyzing reactions relevant to the
synthesis of prebiotic organic
macromolecules (Wächter­shäuser
1990). Wächtershäuser suggested
that metal ions such as iron,
cobalt, and nickel functioned as
catalysts for the synthesis of
organic compounds by fixing
carbon, thus promoting growth of
larger organic molecules and
setting the scene for the origin
of life.
IRON ACQUISITION
In microorganisms, cytochromes are involved in a larger
range of metabolisms because different species can use
different electron donors (i.e. H 2, Fe2+, HS -) and different
electron acceptors (i.e. NO3 -, Fe3+, SO42-). Other key microbial metalloenzymes include nitrogenase, which is used by
the so-called nitrogen-fixing organisms to obtain useable
nitrogen from atmospheric N2 ; hydrogenase, which is used
to produce H 2 from water; and methane monooxygenase,
E lements , V ol . 7,
which is used by a group of
bacteria known as methanotrophs
to oxidize methane to methanol.
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that some species generate different types and amounts of
siderophores depending on the type of iron mineral present
(Page and Huyer 1984). Importantly, different siderophores
are required to sequester Fe(III) from different iron
minerals, and changing the iron mineralogy can elicit a
specific response from the same microorganism. In any
event, siderophores represent an extremely successful solution to the problem of obtaining dissolved ferric iron under
oxygenated conditions.
Gallionella ferruginea has bean-shaped cells that grow at the
terminus of a helical structure called a stalk, which is made
up of polysaccharides. Fe(II) oxidation can generate significant energy at circumneutral pH to support cellular growth.
Interestingly, G. ferruginea does not form a stalk at pH <6,
or under very microaerobic conditions where O2 is present
but the redox potential is –40 mV. This suggests that the
stalk represents an organic surface upon which ferrihydrite
can precipitate and, in doing so, protect the cell itself from
becoming mineralized (Hallbeck and Pederson 1990). In
a similar manner, Nealson (1982) suggested that another
bacterium, Leptothrix ochracea, induces ferrihydrite precipitation on its sheath as a means to remove any free oxygen
and thus detoxify its environment. These examples show
how such bacteria have adapted different strategies for
coping with their unique chemical environment.
AEROBIC Fe(II) OXIDATION
The occurrence of autotrophic bacteria that can synthesize
their own organic compounds and gain energy from the
oxidation of Fe(II) to Fe(III) is generally limited by the
availability of dissolved Fe(II). This is a significant problem
because at neutral pH and under fully aerated conditions,
ferrous iron rapidly oxidizes inorganically to ferric iron,
which then hydrolyzes to ferric (oxyhydr)oxides. The most
efficient way for a bacterium to overcome the stability limitations is to grow either under acidic conditions (such
organisms are known as acidophiles) or under low oxygen
concentrations at circumneutral pH (these are known as
microaerophiles). In both cases the chemical reaction
kinetics are sufficiently diminished that the bacteria can
harness Fe(II) oxidation for growth.
ANAEROBIC Fe(II) OXIDATION
Ferrous iron is relatively stable under anoxic conditions,
but the biological oxidation of Fe(II) may still occur with
nitrate as the electron acceptor via the following reaction
(Straub et al. 1996):
10Fe2+ + 2NO3 − + 24H2O à 10Fe(OH) 3 + N2 + 18H + .
The tolerance of both autotrophic nitrate-reducing and
photosynthetic Fe(II)-oxidizers (see below) to low levels of
oxygen allows them to harvest substrate and energy along,
and partly across, the oxic–anoxic interface where competition with aerobic Fe(II) oxidation could occur. Although
nitrate-dependent Fe(II) oxidation has been shown to be
widespread in sediments (Straub and Buchholz-Cleven
1998), most bacteria that use this metabolism depend on
an organic cosubstrate (e.g. acetate), and truly autotrophic
nitrate-reducing strains have not been isolated in pure
culture. Furthermore, culture studies have demonstrated
that, in fact, a consortium of bacteria is involved in Fe(II)
oxidation coupled with a nitrate-reduction reaction (Blöthe
and Roden 2009). This drives home the point that, in
nature, bacteria typically work in close association with
their neighbors, and a full understanding of biogeochemical cycling of elements requires knowing not only who is
there, but how they interact with one another.
Acidophilic Fe(II)-oxidizing bacteria typically use O2 as an
oxidant—in biology this is referred to as the terminal electron acceptor:
2Fe2+ + 0.5O2 + 2H + à 2Fe3+ + H2O .
The best-characterized acidophiles are Acidothiobacillus
ferrooxidans and Leptospirillum ferrooxidans. They grow well
at mine-waste disposal sites where reduced sources of iron
are continuously generated during acid mine drainage (see
Templeton 2011 this issue). Since it takes on average 50
mol of Fe(II) to assimilate 1 mol of carbon (Silverman and
Lundgren 1959), the acidophiles must oxidize a large
amount of ferrous iron in order to grow. Consequently,
even a small number of bacteria can be responsible for
generating significant concentrations of dissolved Fe(III).
Under neutral pH, but with O2 levels below 1.0 mg per liter
and redox conditions about 200–300 mV lower than those
of typical surface waters (characteristic of some iron
springs, stratified bodies of water, and hydrothermal vent
systems), microaerophilic bacteria such as Gallionella ferruginea play an important role in Fe(II) oxidation and lead
to the formation of ferrihydrite, Fe3+ 4–5 (OH,O)12 (Fig. 1).
One interesting aspect of nitrate-dependent Fe(II) oxidation is that a variety of different Fe(III) minerals (including
magnetite, ferrihydrite, goethite, lepidocrocite, and green
rusts; for mineral definitions, see Taylor and Konhauser
2011 this issue) are formed depending on the geochemical
conditions (e.g. Kappler et al. 2005a) (Fig. 2). Moreover,
Hohmann et al. (2010) recently showed that during iron
biomineralization some toxic metals, such as arsenic, can
be efficiently precipitated. This observation has obvious
environmental significance, suggesting that Fe(II) oxidizing and Fe(III)-mineral-precipitating bacteria have
the potential to influence the fate and mobility of toxic
metal ions in the environment.
PHOTOSYNTHETIC Fe(II) OXIDATION
The existence of anoxygenic photosynthetic Fe(II) oxidation (a form of photosynthesis that does not produce
oxygen, in this case called photoferrotrophy) was suggested
nearly 10 years before the discovery of the first micro­
organisms that actually catalyze this reaction. Hartman
(1984) first proposed photoferrotrophy as a depositional
­mechanism for a class of ancient iron mineral deposits,
the so-called banded iron formations (BIFs), under O2 -free
conditions during the Precambrian (see Poulton and
Canfield 2011 this issue). A decade later, this hypothesis
was validated by the discovery of the first photoferrotrophic microorganisms (Widdel et al. 1993). Since then,
diverse strains of anoxygenic Fe(II)-oxidizing phototrophs,
Iron mineral precipitation as a coating on boulders
from iron- and carbonate-rich mineral water near
Scuol-Tarasp, Engadin, Switzerland. Bacteria exist within the coatings. Photo by A ndreas K appler, U niversity of Tübingen
Figure 1
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low-pH microenvironment immediately around the cell,
the use of organic ligands to keep the Fe(III) in solution
in close cell proximity, or the shedding of organic-mineral
aggregates from the cell surface have all been suggested as
plausible strategies used by the bacteria (Schaedler et al. 2009).
ANAEROBIC Fe(III) REDUCTION
A number of bacterial species heterotrophically break down
existing organic carbon to either carbon dioxide or
methane gas. The type of heterotrophic metabolism that
occurs in nature depends on what oxidants are available
and, in the situation where multiple electron acceptors are
present (as in the uppermost sediment layers), on the
energy yield of the specific reaction. Thus, the decomposition of freshly deposited organic material in sediments
proceeds in a continuous sequence of redox reactions, with
the most electropositive oxidants, such as O2 and NO3,
being consumed at or near the surface and progressively
poorer oxidants, like Mn(IV), Fe(III), SO4, and CO2, being
consumed at depth. Decomposition continues until the
labile organic fraction is exhausted and the deeper sediments are left with a composition very different from that
of the sediments originally deposited (see Konhauser 2007).
Formation of different biogenic Fe(III) minerals during
Fe(II) oxidation by the nitrate-reducing Acidovorax
strain BoFeN1 isolated from Lake Constance sediments (Kappler et
al. 2005a). Cells are partially or fully encrusted by Fe(III) minerals:
the orange globular structures at cell surfaces, blue tabular crystals,
and brown-colored minerals precipitated at a distance from the
cells are all ferric (oxyhydr)oxides of different crystallinity. The cell
in the front is about 1.5–2 µm in length. Scanning electron micro scope image provided by O liver M eckes and N icole O ttawa , Eye of S cience
(www.eyeofscience.com)
Figure 2
Fe(III) reduction occurs below the zone of manganese
reduction and at the depth of complete nitrate removal
from porewaters (see Taylor and Macquaker 2011 this issue).
The reduction of Fe(III) is coupled to the oxidation of H 2
and/or simple fermentation products, including short- and
long-chain fatty acids, alcohols, and various monoaromatic
compounds. The amorphous to poorly ordered iron
(oxyhydr)oxides, such as ferrihydrite, are the preferred
sources of solid-phase ferric iron for Fe(III)-reducing
bacteria (Lovley and Phillips 1987):
including purple sulfur, purple nonsulfur, and green sulfur
bacteria, have been identified. They catalyze this process
according to the following reaction:
4Fe2+ + HCO3 – + 10H2O + light à 4Fe(OH) 3 +
(CH2O) + 7H + .
Photosynthetic Fe(II) -oxidizing bacteria require very
restricted and specialized habitats as they need to be close
to the surface to get light, but they also require a reduced
environment devoid of oxygen because in the presence of
O2 dissolved Fe(II) is rapidly oxidized inorganically.
Accordingly, these microorganisms can circumvent this
problem in two ways. They can tolerate low concentrations
of oxygen, which allows them to live closer to the surface
but requires that the cells oxidize the Fe(II) faster than the
molecular oxygen. Alternatively, they can lower their
requirement for light and thus be able to live deeper in
soils, sediments, and the water column, where the concentration of Fe(II), replenished from below, is higher. In
modern microbial iron-rich mats, light wavelengths that
are useable by the phototrophic Fe(II) oxidizers penetrate
on average about 2–3 mm; therefore, the bacteria must live
in the upper anoxic millimeter of such an environment.
However, Kappler et al. (2005b) demonstrated that, in the
water column, these bacteria are capable of oxidizing Fe(II)
even at very low light intensities (<1% of surface light) and
can grow at a depth below one hundred meters.
CH3COO – + 8Fe(OH)3 à 8Fe2+ + 2HCO3 – + 15OH– + 5H2O .
More-crystalline Fe(III) oxides (e.g. hematite and magnetite) and Fe(III)-rich clay minerals are also microbially
reducible (Fig. 3), and some experimental observations
suggest that these minerals may provide energy for cellular
growth comparable to that derived from the poorly crystalline phases (e.g. Roden and Zachara 1996). The variations
in reductive rates are related to a number of factors,
including the amount of surface area exposure, crystal
morphology, particle aggregation, the composition of the
aqueous solution in which the microorganisms grow, and
the amount of Fe2+ sorbed to the oxide surface. Importantly,
with such wide variations in reactivity towards microbial
reduction, it is not surprising that ferric iron can represent
a long-term electron acceptor for organic matter oxidation,
even at depths where other anaerobic respiratory processes
are thermodynamically predicted to dominate (e.g. Roden
2003).
Until recently, it was believed that the reduction of ferric
iron–containing minerals necessitates direct contact of the
bacterium with the mineral surface. Furthermore, once in
contact with the surface, the Fe(III)-reducers are still faced
with the problem of how to effectively access an electron
acceptor that cannot diffuse into the cell. Some species,
such as Geobacter metallireducens, are able to sense the proximity of oxidized metal, and thereby they move towards
the solid phases. Once in their proximity, the bacteria
specifically express cellular appendages, such as flagella
and pili, to help them adhere to the Fe(III) (oxyhydr)oxides.
Once a bacterium is attached to a mineral surface, it begins
shuttling electrons from a reduced source within its cytoplasm, across the plasma membrane and periplasmic space,
to the outer membrane (e.g. Lower et al. 2001). Reguera et
al. (2005) also suggested that electron transfer via direct
contact between cells and the mineral surface is mediated
via conductive pili known as nanowires.
Both the aerobic and anaerobic Fe(II)-oxidizing bacteria
face the same problem of limited availability of dissolved
Fe(II) and the possible inhibitory effect of the very poor
solubility of the ferric (oxyhydr)oxide end product of their
metabolism. For the stalk- or sheath-forming aerobic Fe(II)oxidizing bacterial genera, Gallionella and Leptothrix, it is
likely that the microbially produced and excreted organic
matrices are used for extracellular capture of Fe(III)
minerals produced. In terms of the photoferrotrophs, it
has recently been proposed that Fe(II) oxidation happens
in the periplasm (the space between the inner and outer
membranes) of the cells (Jiao et al. 2005). However, since
cell encrustation is not observed, this raises the question
of how Fe(III) is transported out of the cytoplasm (the cell
interior) to the cell exterior and then away from the cell
without adsorbing to the outer surface. The presence of a
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SEM image of an
Fe(III)-reducing bacterium, Shewanella putrefaciens CN32,
growing on a crystal of hematite.
Image courtesy of Yuri Gorby and A lice
Dohnalkova , Pacific Northwest
National L aboratory
Figure 3
Banded iron formation from the Dales Gorge Member,
Western Australia. The characteristic banding
comprises brown layers of iron oxides (hematite and magnetite)
and pale layers of chert. The black lens cap gives scale. Photo courtesy of Roger B uick, U niversity of Washington
Figure 4
that such microorganisms could have accounted for all of
the Fe(III) initially deposited in primary BIF sediment
(Kappler et al. 2005b).
Other Fe(III)-reducing bacteria overcome the insolubility
problem by utilizing organic compounds, such as dissolved
humic substances, to shuttle electrons between the cell
surface and the ferric (oxyhydr)oxides, which may be
located at some distance away from the cell (e.g. Roden et
al. 2010). The reduced humic substances subsequently
transfer electrons abiotically to Fe(III), producing Fe(II);
in this process, the oxidized form of the humic compound
is regenerated for another cycle. Significantly, Fe(III) reduction rates are faster in the presence of organic electron
shuttles than in their absence because the organic shuttles
are likely to be more accessible for microbial reduction
than poorly soluble Fe(III) oxyhydroxides (Nevin and
Lovley 2000).
If a biological mechanism was important in the initial
process of Fe(II) oxidation in the ancient ocean water
column, it is expected that biomass would have settled to
the seafloor along with the Fe(III) minerals. This organic
carbon would subsequently have served as an oxidizable
substrate during diagenesis and metamorphism, but the
relevant question is: what terminal electron acceptors were
present at the seafloor? The paucity of O2 would have meant
minimal nitrate and sulfate availability. By contrast, there
was abundant ferric (oxyhydr)oxides deposited as BIF, and
given the presence of partially reduced iron phases such
as magnetite, and to a lesser extent siderite, a microbial
process coupling the oxidation of organic carbon to the
reduction of ferric iron seems very likely (Konhauser et al.
2005). Supporting evidence for an ancient Fe(III) reduction
pathway comes from highly negative d56Fe stable isotope
values in early Archean BIF that are comparable with the
negative fractionations observed from cultures of Fe(III)reducing bacteria (e.g. Johnson et al. 2003).
ANCIENT MICROBIAL Fe METABOLISMS
Obvious geological features intimately tied to ancient
microbial metabolism are banded iron formations, which
were deposited throughout much of the Precambrian. They
are composed of iron-rich (~20–40% Fe) and siliceous
(~40–50% SiO2 ) sedimentary precipitates (Fig. 4). They
have alternating Fe-rich and Si-rich layers that occur on a
wide range of scales. The mineralogy of the least metamorphosed BIF consists predominantly of microcrystalline
quartz, magnetite, hematite, siderite, and iron silicates.
However, it is generally agreed that these minerals reflect
both diagenetic and metamorphic overprinting: the
primary minerals were most likely a combination of ferrihydrite, amorphous silica, and iron-rich clays (Klein 2005).
CONCLUDING REMARKS AND FUTURE
DIRECTIONS
As modern studies demonstrate, bacteria play a key role in
a number of iron transformations in nature (Fig. 5). Yet,
despite our increasing understanding of how microbial
metabolisms affect our surface environment, much remains
to be learned. For instance, how is the modern iron cycle
(i.e. the different Fe-transformation reactions) spatially
It is now generally accepted that the presence of ferric iron
minerals in BIF is due to the metabolic activity of planktonic bacteria in the oceans’ photic zone. Chemical oxidation of Fe(II) by photosynthetically produced O2 is one
possibility, which would allow for the indirect biogenic
precipitation of ferrihydrite. During the Archean (more
than 2.5 billion years ago), this O2 could have been
confined to localized “oxygen oases” associated with
cyanobacterial blooms in coastal settings (Cloud 1965). At
some later stage in the Paleoproterozoic (between 2.5 and
1.6 billion years ago), some Fe(II)-oxidizing bacteria, such
as Gallionella, may even have evolved the means to gain
energy from Fe(II) oxidation (Holm 1989). By 1.89 billion
years ago, iron-rich stromatolites around Lake Superior had
iron isotope values that certainly seem to indicate the existence of Fe(II)-oxidizing bacteria at that time (Planavsky
et al. 2009). It is also plausible that light, not O2, may have
coupled the carbon and iron cycles, via photoferrotrophy
as described above (Hartman 1984). Experimentally determined photosynthetic Fe(II) oxidation rates even suggest
E lements
Microbial Fe(III)-reduction (white arrows) and Fe(II)oxidation (black arrows) processes in acidic and
circumneutral pH environments under oxic and anoxic conditions.
Figure courtesy of C aroline Schmidt, U niversity of Tübingen
Figure 5
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structured in various environments, particularly at the
aerobic–anaerobic interface in natural waters, sediment, or
soils, where Fe(II)-oxidizing and Fe(III)-reducing bacteria
may live within millimeter- to centimeter-scale redox gradients? Significant interest is also being directed at understanding how crucial bacteria were in the ancient iron
cycle. In terms of BIF, were bacteria the dominant oxidizers
of dissolved Fe(II)? Similarly, did the evolution of microbial
iron metabolisms leave a signature in the ancient rock
record? The search for answers to these questions will be
facilitated only by applying an increasingly broad spectrum
of geochemical, microbiological, and molecular genetic/
genomic tools to the study of the internal complexity of
modern Fe-rich environments. Therefore, our ability to
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A pr il 2011
ESF Research Network Programme
ESF Research Network Programme
ESF Research Network Programme
Functionality of Iron Minerals (FIMIN) established
The European Science Foundation
(ESF) Research Network
Programme Functionality of Iron
Minerals (FIMIN) was established
in 2009.
FIMIN relies and builds on existing
national and international projects
and initiatives dedicated to the
understanding of the chemical and
biological fundamentals of surface
processes and iron mineral transformation reactions. FIMIN operates
along the following research themes:
• The role of iron oxide surfaces
in biogeochemistry
• Iron as a key redox species in
microbiological processes
• Environmental biogeochemistry
of iron
• Techniques to identify processes
related to the biogeochemistry
of iron
The ultimate goal of FIMIN is to
elucidate the functionality of iron
minerals. Cycling of electrons and
matter through iron minerals is relevant to contrasting disciplines in the
environmental sciences, including
geochemistry, biogeochemistry,
microbiology, soil and hydrological
sciences, and biotechnology. FIMIN
therefore aims to:
• Improve our understanding of
the surface reactivity of iron
minerals from a mechanistic
point of view
• Understand the mechanisms and
strategies microorganisms adopt
to cope with surface chemical
constraints
• Integrate this knowledge into the
modelling and quantification of
electron fluxes in natural systems
• Develop sound strategies to make
use of the functionality of iron
minerals in (bio)technological
applications
PROGRAMME
FIMIN strives to integrate scientists
working on scales ranging from
molecular geochemistry, through
reactor dimension and catchment
size, to the global scale, using
diverse methods (e.g. spectroscopy,
geochemical techniques, stable
isotope techniques, molecular
biology, microbiology, field techniques and modelling) and investigating various environmental
systems (e.g. soils, sediments, waters
and remediation systems). Primarily,
FIMIN will promote and facilitate
E lements
exchange of knowledge and materials,
as well as access to and support of
analytical equipment and potential
study sites.
The following initiatives will serve
to stimulate mutual learning within
the Programme:
• Provide a platform for European
researchers of different disciplines to promote and integrate
various concepts and techniques
related to the understanding of
the functionality of iron in
natural and anthropogenic
processes
• Facilitate exchange of know-how
and materials (microbes, cultivation techniques, reference
minerals, preparation procedure)
• Initiate new research activities
that utilise state-of-the-art
­techniques and technologies for
studying the role of iron in environmental (bio)geochemistry
• Provide means, including
exchange visits, conferences,
workshops, summer schools,
common databases and an interactive web page
• Enable access to analytical equipment and interesting field sites
• Provide opportunities for training
young investigators in the latest
advances in relevant techniques
Several tools exist to support these
initiatives:
Long- and short-term exchange
grants for researchers are provided
to enable visits to institutions in
other participating countries. Calls
for grants are made, with application
deadlines on 15 October, 15
February and 15 June of each year.
Scientific workshops will be
organised or supported and will
focus on specific topics:
• 25 May–9 June 2010, in Lund,
Sweden, and Lyngby and
Copenhagen, Danemark:
Magnetic Methods in
Biogeochemistry – From Field
to Microscopy and Mössbauer
Spectroscopy (Christian Bender
Koch and Mihály Pósfai)
• 7–11 August 2011, in Tübingen,
Germany: Tools in Environ­
mental Biogeochemistry –
Opportunities and Limitations
(Andreas Kappler and Ruben
Kretzschmar)
94
• Late 2011, early 2012, in the
United Kingdom: Environmental
Iron Microbiology (Jon Lloyd and
Barrie Johnson)
• 2012, in Vienna, Austria: The Use
of Stable Isotopes of Fe in
Environmental Geochemistry
and Biogeochemistry (Stephan
Kraemer and Yigal Erel)
A spring school entitled Iron in
the Environment: From Nature to
the Laboratory was set up for junior
researchers interested in the nature
and dynamics of iron and iron
minerals in natural environments
(7–11 March 2011, in Cordoba,
Spain; Jose Torrent, Eric Smolders,
Thilo Behrends, Stefan Peiffer). It
dealt with iron in soils, sediments,
surface water and groundwater, and
geological systems. Reviews on iron
minerals and their environmental
significance, as well as on the principles and state of the art of analytical techniques were presented.
All scientists active in any of the
FIMIN research themes are encouraged to apply for our programmes.
Applications will be selected based
on scientific excellence and in accordance with ESF priority rules (www.
esf.org/RNP-guidelines).
For more and up-to-date information, please visit the FIMIN websites:
www.fimin.eu and www.esf.
org/fimin.
STEERING COMMITTEE
S. PEIFFER (Chair), Department of
Hydrology, University of Bayreuth,
Germany
T. BEHRENDS, Department of Earth
Sciences – Geochemistry, Faculty of
Geosciences, Utrecht University,
the Netherlands
Y. EREL, Institute of Earth Sciences,
The Hebrew University, Israel
C. B. KOCH, Department of Basic Science
and Environment, Faculty of Life
Science, University of Copenhagen,
Denmark
S. KRAEMER, Center for Geosciences,
University of Vienna, Austria
R. KRETZSCHMAR, Institute of
Biogeochemistry and Pollutant
Dynamics, ETH Zürich, Switzerland
L. LÖVGREN, Department of Chemistry,
University of Umeå, Sweden
M. PÓSFAI, Department of Earth and
Environmental Sciences, University
of Pannonia, Hungary
E. SMOLDERS, Katholieke Universiteit
Leuven, Soil and Water Control,
Belgium
J. TORRENT, Departamento de Ciencias
y Recursos Agrícolas y Forestales,
Universidad de Córdoba, Spain
A pr il 2011